%I A055267
%S A055267 1,7,20,53,139,364,953,2495,6532,17101,44771,117212,306865,803383,
%T A055267 2103284,5506469,14416123,37741900,98809577,258686831,677250916,
%U A055267 1773065917,4641946835,12152774588,31816376929,83296356199
%N A055267 a(n)=3a(n-1)-a(n-2); a(0)=1, a(1)=7.
%D A055267 I. Adler, Three Diophantine equations - Part II, Fib. Quart., 7 (1969), 
               pps. 181-193.
%D A055267 A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, 
               pps. 122-125, 194-196.
%D A055267 E. I. Emerson, Recurrent Sequences in the Equation DQ^2=R^2+N, Fib. Quart.,
               7 (1969), pps. 231-242.
%H A055267 <a href="Sindx_Rea.html#recLCC">Index entries for sequences related to 
               linear recurrences with constant coefficients</a>
%H A055267 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/
               RecursiveSequences.html">Recursive Sequences</a>
%F A055267 a(n)={7*[((3+sqrt(5))/2)^n-((3-sqrt(5))/2)^n]-[((3+sqrt(5))/2)^(n-1)-((3-sqrt(5))/
               2)^(n-1)]}/sqrt(5).
%e A055267 G.f.=(1+4x)/(1-3x+x^2)
%Y A055267 Cf. A054492 and A054486.
%Y A055267 Sequence in context: A007044 A047862 A048755 this_sequence A009370 A009372 
               A051102
%Y A055267 Adjacent sequences: A055264 A055265 A055266 this_sequence A055268 A055269 
               A055270
%K A055267 easy,nonn
%O A055267 0,2
%A A055267 Barry E. Williams, May 09 2000